Lithium CPS have a number of the qualities advantageously differing them from traditional power sources. They are characterized by the increased values of discharge voltage (from 1.5 up to 4.5 V), high specific energy power characteristics, long life, long time of storage and wide operation temperature ranger. Specific characteristics of lithium CPS calculated by thermodynamic method reach more 1000 (W·h)·kg−1.
In spite of the successes in the development and numerous advantages in lithium CPS it became necessary to increase the efficiency of their work. In particular, at this moment, the problem concerning lithium dendritic growth and capacity loss at lithium electrode cycling is still unsolved.
Use of solid inorganic electrolytes (SE) will enable design of new generation lithium (CPS) with the possibility of safe redischarging, temperature range widening and new standard sizes. At the given moment a great number of SE is recognized for application in lithium CPS.
Lithium secondary power sources with a solid electrolyte have essential advantages as compared with the lithium secondary power sources with a liquid electrolyte.
The following advantages may be considered as the main ones:                a high specific characteristics due to the possibility to use metal lithium as the anode of lithium-metal secondary batteries;        increased safety at lithium-metal secondary battery cycling due to the absence of treeing and short circuits between cathode and anode;        unavailability of liquid phase, and, hence, possibility of the reliable hermetic sealing of power source;        possibility to manufacture the completely solid-phase micro batteries with the thickness up to micro units.        
To realize the advantages of lithium power sources with a solid electrolyte, the latter should possess the following main properties:                high lithium cation ionic conductivity at room temperatures;        low electronic conductivity to avoid power source self-discharge;        chemical stability relative to electrode materials and the products of electrochemical reactions in the process of power source discharge-charge;        electrochemical stability in the working voltage range of power source cycling;        possibility to produce SE as thin films (in particular, for thin film production from vitreous materials, these materials should melt and then solidify without destruction).        
Goal this invention is development solid inorganic electrolyte and method of production thereof which will satisfy these requests.
High lithium ion conductivity of solid inorganic vitreous materials is determined by both the significant content of lithium oxide in their composition, and the increased values of a free volume typical of vitreous materials (especially in a hardened state).
All the materials with cation conductivity which can be used as solid electrolyte in electrochemical cells may be conventionally subdivided into crystalline and amorphous ones.
For the above aim, among crystalline materials the so-called β-alumina (Li2O·5A12O3 or Li2O11A12O3), which conductivity is 5·10−2 S·cm−1 at 100° C. and 5·10−1 S·cm−1 at 300° C. is of the greatest interest. Application of β-alumina for the noted aim is limited by the difficulty connected with producing monolithic products as thin films. Primarily, it is connected with the incongruent melting character of crystalline compounds of the above composition, i.e. with their irreversible destruction at heating above melting temperature (above 1500° C., for example, at evaporation in vacuum. Besides, the above compounds are characterized by clearly expressed anisotropy. According to the literature data the mentioned conductivity values are observed only alongside axis perpendicular to the main axis of crystals, in the other directions β-alumina is characterized by considerably less conductivity.
Such crystalline compounds as Li2SO4 and Li2WO4, are also characterized by rather high values of lithium ion conductivity, however, on the judgment of the majority of investigators this concerns only the high temperature modifications of the mentioned crystals [2].
It is also known the U.S. Pat. No. 3,911,083, where oxyhalogenide crystalline cation conductors with lithium ion conductivity close to β-alumina being characterized by rather lower melting temperature are described. In particular, melting temperature of the compound corresponding to the formula Li4B7O12Cl is only 850° C., and its conductivity at 300° C. is close to 10-2 S·cm−1. Nevertheless, high conductivity of the proposed materials is reached only at high temperatures (the data concerning conductivity of such materials at room temperature are unavailable in the literature) whereas, solid electrolyte, primarily, should provide stable work in the composition of CPS at room temperature.
At present, vitreous solid electrolytes are widespread [3]. Due to the statistical distribution of structural elements in glass (glass networks) they are characterized by higher disorder degree and increased (as compared with the corresponding crystals) free volume (especially, hardened glasses). These factors promote increasing ionic conductivity of glassy materials.
All amorphous solid electrolytes described in the literature can be arbitrarily subdivided into oxygen-free (sulfide, halogenide, etc), oxygen-comprising and mixed ones.
Lithium-comprising sulfide glasses are characterized by the exclusively high values of lithium ion conductivity (according to the literary date, their conductivity reaches 10−4÷10−3 S·cm−1 at room temperature). Complex technology of their production, (in particular, synthesis of sulfide glasses can be realized either under vacuum conditions or in shielding atmosphere) is the characteristic disadvantage of such glasses. Well-known tendency of sulfides to a hydrolysis conditions their low chemical stability. Besides, at storage in air the partial oxidation of S2-cations inevitably results in increasing the electron component of such glass composition conductivity. Electrical stability of sulfide SE also causes a doubt.
Multi-lithium halogenide and oxihalogenide glasses have been investigated rather well. It is generally accepted, that introduction of lithium salts into lithium-borate glasses improves significantly their conductivity. In particular, U.S. Pat. No. 4,184,015 describes the glasses comprising 1B2O3·(0.57-0.85)Li2O·(0.21-0.57)LiCl, which conductivity at 100° C. is 6.3·10−6 -1.1·10−4 S·cm−1. However, taking into account the fact that battery operation with solid electrolyte should occur at lower temperatures, one may conclude that the glasses of the above composition have insufficiently high ionic conductivity.
Solid electrolytes based on oxide glasses [2,3] have been investigated the most widely. It should be noted that oxide glasses as compared with the non-oxygen ones have the indisputable advantages—chemical and electrochemical stability. Correspondingly, they are produced directly in air. The majority of such glasses as glass-forming oxides comprises B2O3 and P2O5, i.e. is based on the glass-forming systems Li2O—B2O3 and Li2O—P2O5. For increasing ionic conductivity of such glasses oxygen-comprising lithium salts are included [3]. In the literature the glass including 0.4Li2O·0.2Li2SO4·0.4B2O3 [4], which was used in the compositions with polyethylene oxide as CPS electrolyte is described.
In the U.S. Pat. No. 4,184,015, selected by the author as a prototype, there is information about the conductivity of the glass including 0.57Li2O·0.29Li2SO4·1B2O3, which was 2·10−5 S·cm−1 at 100° C. However, at room temperature lithium ion conductivity of these glasses is insufficient for normal work as a solid electrolyte of CPS.